A supported manganese-based catalyst, its preparation method and use in the preparation of o-chlorobenzoic acid

Abstract

The present application relates to the technical field of catalyst synthesis, in particular to a supported manganese-based catalyst, a preparation method thereof and application of the catalyst in preparation of o-chlorobenzoic acid. The supported manganese-based catalyst comprises an active component and a carrier, wherein the carrier is SiO2, and the active component is a mixture of manganese oxide and cobalt oxide; the preparation method comprises the following steps: dissolving Na2SiO3.9H2O, sulfuric acid, a manganese-cobalt mixture and Na2CO3 in water respectively to obtain solution A, solution B, solution C and solution D; under water bath condition, solution A is introduced into a first micro-reactor as a dispersed phase through a metering pump, mixed with continuous phase solution B, flows through a first residence tube, mixed with solution C through a T-shaped three-way joint, and then introduced into a second residence tube, and then introduced into a second micro-reactor to be mixed with dispersed phase solution D, and then introduced into a polytetrafluoroethylene reaction tube, and then the precipitate is collected after reaction; and then the precipitate is centrifuged, washed, dried and calcined. The preparation method is simple, and the catalyst has excellent catalytic activity and stability.

Description

Technical Field

[0001] This invention relates to the field of catalyst synthesis technology, specifically to a supported manganese-based catalyst, its preparation method, and its application in the preparation of o-chlorobenzoic acid. Background Technology

[0002] o-Chlorobenzoic acid is a colorless needle-like crystal or white powder, widely used in the pharmaceutical, pesticide, and dye industries as an important organic synthesis intermediate and analytical reagent. In pharmaceuticals, it is primarily used in the synthesis of antipsychotics such as perphenazine, adrenocorticotropic agents such as zenbufenozide and thiamethoxam, antifungal agents such as chlorpromazine, clotrimazole, antifungal agents, ketamine, mebendazole, and diclofenac, and fungicides such as fluoropyrimidine alcohol. In pesticides, it is an intermediate in the synthesis of insecticides such as diflubenzuron and chlorfluazuron, and the highly effective, low-toxicity acaricide tetradifon. In analytical applications, it serves as a standardized reagent for alkaline titration and iodometric titration. Furthermore, it is used in the production of adhesives, preservatives in coatings, synthetic dyes, and color films.

[0003] The synthesis methods for o-chlorobenzoic acid mainly include chlorination hydrolysis, diazotization, chemical oxidation, and catalytic oxidation. Chlorination hydrolysis and diazotization methods suffer from equipment corrosion, high production costs, and the generation of large amounts of waste liquid and waste gas that easily pollute the environment, leading to their gradual phasing out in chemical production. Chemical oxidation has a relatively mild reaction process, is easy to control, and is relatively simple to operate; however, the cost of oxidants used in chemical oxidation is generally high, thus its application is only widespread for some low-volume, high-value chemical products. Catalytic oxidation is a highly promising green synthesis route; however, traditional catalytic oxidation processes either require the use of highly corrosive solvents, leading to serious environmental pollution and equipment corrosion problems, or suffer from low o-chlorotoluene conversion rates and low selectivity for the target product.

[0004] Therefore, there is an urgent need to develop a catalyst system with superior performance to achieve the directional oxidative conversion of o-chlorotoluene in a solvent-free system, thereby improving the selectivity and yield of the reaction. Constructing an atom-economical and environmentally friendly process for the catalytic oxidation of o-chlorotoluene to o-chlorobenzoic acid based on this catalyst has significant application value. Summary of the Invention

[0005] In view of this, the present invention provides a supported manganese-based catalyst, its preparation method and its application in the preparation of o-chlorobenzoic acid, aiming to solve the technical problems in the prior art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: In a first aspect, a supported manganese-based catalyst is provided, comprising: an active component and a support, wherein the support is SiO2 and the active component is a mixture of manganese oxide and cobalt oxide.

[0007] Secondly, a method for preparing a supported manganese-based catalyst is provided, the method comprising: Step S1: Dissolve Na2SiO3·9H2O, sulfuric acid, manganese-cobalt mixture and Na2CO3 in water to obtain solution A, solution B, solution C and solution D respectively; Step S2: Under water bath conditions, solution A is introduced into the first microreactor as the dispersed phase by a metering pump, mixed with the continuous phase solution B, and then flows through the first residence tube. After mixing with solution C through a T-type tee, it is introduced into the second residence tube and then into the second microreactor, where it is mixed with the dispersed phase solution D. The mixture is then introduced into a polytetrafluoroethylene reaction tube, and the precipitate is collected after the reaction. Step S3: After centrifugation, washing, drying and calcination, the precipitate is obtained as the supported manganese-based catalyst.

[0008] A further improvement of the present invention is that, in step S1, the concentration of Na2SiO3·9H2O in solution A is 0.01-0.5 mol / L, preferably 0.01-0.2 mol / L; the concentration of sulfuric acid in solution B is 0.05-0.5 mol / L; the manganese-cobalt mixture includes MnCl2·4H2O and Co(NO3)2·6H2O in a molar ratio of 1:0.05-1.0 (preferably 1:0.25-1.0); the total concentration of metal salts in solution C is 0.1-0.5 mol / L; and the concentration of Na2CO3 in solution D is 0.1-1.0 mol / L, preferably 0.25-0.5 mol / L.

[0009] A further improvement of the present invention is that, in step S2, the water bath temperature is 20-50℃; the flow rates of solution A and solution C are the same, which is 3-7.5 mL / min; and the flow rate of solution B is adjusted so that the pH value of the solution after mixing solution A and solution B is 8.3-8.7.

[0010] A further improvement of the present invention is that, in step S2, both the first microreactor and the second microreactor are membrane dispersion mixers, and the stainless steel microfiltration membrane of the membrane dispersion mixer has a pore size of 0.5-5 μm and a diameter of 6.5-100 mm.

[0011] A further improvement of the present invention is that, in step S2, both the first residence tube and the second residence tube are polytetrafluoroethylene tubes with an inner diameter of 3 mm; the residence time in the first residence tube is 5-20 min, and the residence time in the second residence tube is 3-10 min; the volume of the polytetrafluoroethylene reaction tube is 50 mL, and the inner diameter is 3 mm.

[0012] A further improvement of the present invention is that, in step S3, the drying temperature is 90-110℃, preferably 100℃; the calcination temperature is 450-800℃; the calcination time is 3.5-4.5h, preferably 4h; and the heating rate is 3-7℃ / min, preferably 5℃ / min.

[0013] Thirdly, a method for preparing o-chlorobenzoic acid is provided, which uses a supported manganese-based catalyst as described in the first aspect or a supported manganese-based catalyst prepared by the method described in the second aspect as a catalyst, and catalyzes the preparation of o-chlorobenzoic acid from o-chlorotoluene under oxygen-introduced conditions.

[0014] A further improvement of the present invention is that the weight ratio of o-chlorotoluene to the catalyst is 1:0.18~0.22, preferably 1:0.2; and under standard conditions, the oxygen introduction rate is 240-260 ml / min, preferably 250 ml / min.

[0015] A further improvement of the present invention is that the reaction temperature is 130-160℃ and the reaction time is 8-14h.

[0016] The technological advancements achieved by this invention due to the adoption of the above technical solutions are as follows: The supported manganese-based catalyst of the present invention is continuously prepared using a micromixer and does not use precious metals. The preparation method is simple and the catalyst cost is low.

[0017] Furthermore, the supported catalyst prepared by this method can oxidize o-chlorotoluene to o-chlorobenzoic acid via molecular oxygen. The reaction is carried out under solvent-free conditions at atmospheric pressure, requiring minimal equipment and demonstrating economic feasibility. The reaction also generates minimal waste. The conversion rate of o-chlorotoluene is 99.3%, and the yield of o-chlorobenzoic acid is 98.2%. The catalyst was recycled five times without any decline in catalytic performance. Therefore, this catalyst exhibits excellent catalytic activity and stability in catalytic oxidation reactions and shows promising application prospects. Detailed Implementation

[0018] The technical solutions in the embodiments of the present invention will be clearly and completely described below.

[0019] Preparation Example 1: Preparation of 0.9MnOX-0.1Co3O4 / 0.1SiO2 at 450°C (temperature) Step S1: Prepare a 0.01 mol / L Na2SiO3·9H2O solution (A), a 0.05 mol / L sulfuric acid solution (B), a mixed solution of 0.09 mol / L MnCl2·4H2O and 0.01 mol / L Co(NO3)2·6H2O (C, the molar ratio of MnCl2·4H2O to Co(NO3)2·6H2O is 9:1), and prepare a 0.25 mol / L Na2CO3 solution (D).

[0020] Step S2: In a 20°C water bath, solution A is introduced into the first membrane dispersion microreactor at a rate of 3 mL / min using a metering pump. It is mixed with the continuous phase solution B (the pH of the mixed solution is adjusted to 8.3 by adjusting the flow rate of solution B). Then, the material is allowed to remain in the first residence tube for 5 minutes by adjusting the length of the first residence tube. After mixing with solution C (flow rate 3 mL / min) through a T-junction, the mixture is introduced into the second residence tube and left to remain for 3 minutes. It is then introduced into the second membrane dispersion microreactor and mixed with solution D (flow rate 3 mL / min). Finally, a 50 mL polytetrafluoroethylene tube with an inner diameter of 3 mm is introduced, and the precipitate is collected after the reaction.

[0021] Step S3: The precipitate is centrifuged, washed with deionized water until neutral, dried at 100℃, and then calcined at 450℃ for 4h at a rate of 5℃ / min to obtain catalyst 0.9MnOX-0.1Co3O4 / 0.1SiO2-450.

[0022] Example 2: Preparation of 0.8MnOX-0.2Co3O4 / 0.2SiO2-600 Step S31: Prepare a 0.1 mol / L Na2SiO3·9H2O solution (A), a 0.2 mol / L sulfuric acid solution (B), a mixed solution of 0.4 mol / L MnCl2·4H2O and 0.1 mol / L Co(NO3)2·6H2O (C, the molar ratio of MnCl2·4H2O to Co(NO3)2·6H2O is 8:2), and prepare a 0.8 mol / L Na2CO3 solution (D).

[0023] Step S2: In a 30°C water bath, solution A is introduced into the first membrane dispersion microreactor at a rate of 4 mL / min using a metering pump. It is then mixed with the continuous phase solution B (the pH of the mixed solution is adjusted to 8.5 by adjusting the flow rate of solution B). After the material has been held in the first residence tube for 15 min by adjusting the length of the first residence tube, it is mixed with solution C (flow rate 4 mL / min) through a T-junction and then introduced into the second residence tube for 8 min. It is then introduced into the second membrane dispersion microreactor and mixed with solution D (flow rate 4 mL / min). Finally, it is introduced into a 50 mL polytetrafluoroethylene tube with an inner diameter of 3 mm. The precipitate is collected after the reaction.

[0024] Step S3: The precipitate is centrifuged, washed with deionized water until neutral, dried at 100℃, and then calcined at 600℃ for 4 hours at a rate of 5℃ / min to obtain catalyst 0.8MnOX-0.2Co3O4 / 0.2SiO2-600.

[0025] Preparation Example 3: Preparation of 0.7MnOX-0.3Co3O4 / 0.2SiO2-700 Step S1: Prepare a 0.04 mol / L Na2SiO3·9H2O solution (A), a 0.1 mol / L sulfuric acid solution (B), a mixed solution of 0.14 mol / L MnCl2·4H2O and 0.06 mol / L Co(NO3)2·6H2O (C, the molar ratio of MnCl2·4H2O to Co(NO3)2·6H2O is 7:3), and prepare a 0.4 mol / L Na2CO3 solution (D).

[0026] Step S2: In a 40℃ water bath, solution A is introduced into the first membrane dispersion microreactor at a rate of 5 mL / min using a metering pump. It is mixed with the continuous phase solution B (the pH of the mixed solution is adjusted to 8.7 by adjusting the flow rate of solution B). Then, the material is allowed to remain in the first residence tube for 20 minutes by adjusting the length of the first residence tube. After mixing with solution C (flow rate 5 L / min) through a T-junction, the mixture is introduced into the second residence tube and left to remain for 10 minutes. It is then introduced into the second membrane dispersion microreactor and mixed with solution D (flow rate 5 mL / min). Finally, a 50 mL polytetrafluoroethylene tube with an inner diameter of 3 mm is introduced, and the precipitate is collected after the reaction.

[0027] Step S3: The precipitate is centrifuged, washed with deionized water until neutral, dried at 100℃, and then calcined at 700℃ for 4 hours at a rate of 5℃ / min to obtain catalyst 0.7MnOX-0.3Co3O4 / 0.2SiO2-700.

[0028] Preparation Example 4: Preparation of 0.5MnOX-0.5Co3O4 / 1.0SiO2-800 Step S1: Prepare a 0.2 mol / L Na2SiO3·9H2O solution (A), a 0.5 mol / L sulfuric acid solution (B), a mixed solution of 0.1 mol / L MnCl2·4H2O and 0.1 mol / L Co(NO3)2·6H2O (C, the molar ratio of MnCl2·4H2O to Co(NO3)2·6H2O is 1:1), and prepare a 0.25 mol / L Na2CO3 solution (D).

[0029] Step S2: In a 50℃ water bath, solution A is introduced into the first membrane dispersion microreactor at a rate of 7.5 mL / min using a metering pump. It is mixed with the continuous phase solution B (the pH of the mixed solution is adjusted to 8.4 by adjusting the flow rate of solution B). Then, the material is allowed to remain in the first residence tube for 20 min by adjusting the length of the first residence tube. After mixing with solution C (flow rate 7.5 mL / min) through a T-junction, the mixture is introduced into the second residence tube and left to remain for 10 min. It is then introduced into the second membrane dispersion microreactor and mixed with solution D (flow rate 7.5 mL / min). Finally, a 50 mL polytetrafluoroethylene tube with an inner diameter of 3 mm is introduced, and the precipitate is collected after the reaction.

[0030] Step S3: The precipitate is centrifuged, washed with deionized water until neutral, dried at 100℃, and then calcined at 800℃ for 4 hours at a rate of 5℃ / min to obtain catalyst 0.5MnOX-0.5Co3O4 / 1.0SiO2-800.

[0031] Preparation Example 5: Preparation of 0.7MnOX-0.3Co3O4 / 0.2SiO2-700 Step S1: Prepare a 0.02 mol / L Na2SiO3·9H2O solution (A), a 0.05 mol / L sulfuric acid solution (B), a mixed solution of 0.07 mol / L MnCl2·4H2O and 0.03 mol / L Co(NO3)2·6H2O (C, the molar ratio of MnCl2·4H2O to Co(NO3)2·6H2O is 7:3), and prepare a 0.25 mol / L Na2CO3 solution (D).

[0032] Step S2: In a 40℃ water bath, solution A is introduced into the first membrane dispersion microreactor at a rate of 7.5 mL / min using a metering pump. It is mixed with the continuous phase solution B (the pH of the mixed solution is adjusted to 8.5 by adjusting the flow rate of solution B). Then, the material is allowed to remain in the first residence tube for 20 min by adjusting the length of the first residence tube. After mixing with solution C (flow rate 7.5 mL / min) through a T-junction, the mixture is introduced into the second residence tube and left to remain for 10 min. It is then introduced into the second membrane dispersion microreactor and mixed with solution D (flow rate 7.5 mL / min). Finally, a 50 mL polytetrafluoroethylene tube with an inner diameter of 3 mm is introduced. The precipitate is collected after the reaction.

[0033] Step S3: The precipitate is centrifuged, washed with deionized water until neutral, dried at 100℃, and then calcined at 700℃ for 4 hours at a rate of 5℃ / min to obtain catalyst 0.7MnOX-0.3Co3O4 / 0.2SiO2-700.

[0034] Preparation Example 6: Preparation of 0.7MnOX-0.3Co3O4 / 0.3SiO2-700 Step S1: Prepare a 0.06 mol / L Na2SiO3·9H2O solution (A), a 0.1 mol / L sulfuric acid solution (B), a mixed solution of 0.14 mol / L MnCl2·4H2O and 0.06 mol / L Co(NO3)2·6H2O (C, the molar ratio of MnCl2·4H2O to Co(NO3)2·6H2O is 7:3), and prepare a 0.4 mol / L Na2CO3 solution (D).

[0035] Step S2: In a 40℃ water bath, solution A is introduced into the first membrane dispersion microreactor at a rate of 7.5 mL / min using a metering pump. It is mixed with the continuous phase solution B (the pH of the mixed solution is adjusted to 8.5 by adjusting the flow rate of solution B). Then, the material is allowed to remain in the first residence tube for 20 minutes by adjusting the length of the first residence tube. After mixing with solution C (flow rate 7.5 mL / min) through a T-junction, the mixture is introduced into the second residence tube and left to remain for 10 minutes. It is then introduced into the second membrane dispersion microreactor and mixed with solution D (flow rate 7.5 mL / min). Finally, a 50 mL polytetrafluoroethylene tube with an inner diameter of 3 mm is introduced, and the precipitate is collected after the reaction.

[0036] Step S3: The precipitate is centrifuged, washed with deionized water until neutral, dried at 100℃, and then calcined at 700℃ for 4 hours at a rate of 5℃ / min to obtain catalyst 0.7MnOX-0.3Co3O4 / 0.3SiO2-700.

[0037] Preparation Example 7: Preparation of 0.7MnOX-0.3Co3O4 / 0.4SiO2-700 Step S1: Prepare a 0.08 mol / L Na2SiO3·9H2O solution (A), a 0.2 mol / L sulfuric acid solution (B), a mixed solution of 0.14 mol / L MnCl2·4H2O and 0.06 mol / L Co(NO3)2·6H2O (C, the molar ratio of MnCl2·4H2O to Co(NO3)2·6H2O is 7:3), and prepare a 0.5 mol / L Na2CO3 solution (D).

[0038] Step S2: In a 40℃ water bath, solution A is introduced into the first membrane dispersion microreactor at a rate of 7.5 mL / min using a metering pump. It is mixed with the continuous phase solution B (the pH of the mixed solution is adjusted to 8.6 by adjusting the flow rate of solution B). Then, the material is allowed to remain in the first residence tube for 20 minutes by adjusting the length of the first residence tube. After mixing with solution C (flow rate 7.5 mL / min) through a T-junction, the mixture is introduced into the second residence tube and left to remain for 10 minutes. It is then introduced into the second membrane dispersion microreactor and mixed with solution D (flow rate 7.5 mL / min). Finally, a 50 mL polytetrafluoroethylene tube with an inner diameter of 3 mm is introduced, and the precipitate is collected after the reaction.

[0039] Step S3: The precipitate is centrifuged, washed with deionized water until neutral, dried at 100℃, and then calcined at 700℃ for 4 hours at a rate of 5℃ / min to obtain catalyst 0.7MnOX-0.3Co3O4 / 0.4SiO2-700.

[0040] Example 8: Preparation of 0.7MnOX-0.3Co3O4 / 0.5SiO2-700 Step S1: Prepare a 0.1 mol / L Na2SiO3·9H2O solution (A), a 0.2 mol / L sulfuric acid solution (B), a mixed solution of 0.14 mol / L MnCl2·4H2O and 0.06 mol / L Co(NO3)2·6H2O (C, the molar ratio of MnCl2·4H2O to Co(NO3)2·6H2O is 7:3), and prepare a 0.4 mol / L Na2CO3 solution (D).

[0041] Step S2: In a 40℃ water bath, solution A is introduced into the first membrane dispersion microreactor at a rate of 7.5 mL / min using a metering pump as the dispersed phase. It is mixed with the continuous phase solution B (the pH of the mixed solution is adjusted to 8.3 by adjusting the flow rate of solution B). Then, the material is allowed to remain in the first residence tube for 20 minutes by adjusting the length of the first residence tube. After mixing with solution C (flow rate 7.5 mL / min) through a T-junction, the mixture is introduced into the second residence tube and left to remain for 10 minutes. It is then introduced into the second membrane dispersion microreactor and mixed with solution D (flow rate 7.5 mL / min). Finally, a 50 mL polytetrafluoroethylene tube with an inner diameter of 3 mm is introduced, and the precipitate is collected after the reaction.

[0042] Step S3: The precipitate is centrifuged, washed with deionized water until neutral, dried at 100℃, and then calcined at 700℃ for 4 hours at a rate of 5℃ / min to obtain catalyst 0.7MnOX-0.3Co3O4 / 0.5SiO2-700.

[0043] Example 1: Catalytic oxidation of o-chlorotoluene to prepare o-chlorobenzoic acid 500 g of o-chlorotoluene was added to a 1000 ml glass reaction flask, along with 10.0 g of the catalyst obtained in Preparation Example 1 (2% of the mass of o-chlorotoluene). The mixture was heated to 130 °C, and oxygen was introduced at a rate of 250 ml / min (standard conditions). After reacting for 4 hours, the temperature was raised to 145 °C, and the reaction was continued for 10 hours while maintaining the same temperature and oxygen introduction rate. The mixture was then filtered while hot after the reaction was complete, and the filtrate was quantitatively analyzed by gas chromatography (internal standard method). The conversion rate of o-chlorotoluene was 90.6%, and the yield of o-chlorobenzoic acid was 80.7%.

[0044] Example 2: Catalytic oxidation of o-chlorotoluene to prepare o-chlorobenzoic acid 500 g of o-chlorotoluene was added to a 1000 ml glass reaction flask, along with 10.0 g of the catalyst obtained in Preparation Example 2 (2% of the mass of o-chlorotoluene). The mixture was heated to 130 °C, and oxygen was introduced at a rate of 250 ml / min (standard conditions). After reacting for 4 hours, the temperature was raised to 155 °C, and the reaction was continued for another 8 hours while maintaining the same temperature and oxygen introduction rate. The mixture was then filtered while hot after the reaction was complete, and the filtrate was quantitatively analyzed by gas chromatography (internal standard method). The conversion rate of o-chlorotoluene was 95.1%, and the yield of o-chlorobenzoic acid was 90.6%.

[0045] Example 3: Catalytic oxidation of o-chlorotoluene to prepare o-chlorobenzoic acid 500 g of o-chlorotoluene was added to a 1000 ml glass reaction flask, along with 10.0 g of the catalyst obtained in Preparation Example 3 (2% of the mass of o-chlorotoluene). The mixture was heated to 130 °C, and oxygen was introduced at a rate of 250 ml / min (standard conditions). After reacting for 3 hours, the temperature was raised to 160 °C, and the reaction was continued for another 7 hours while maintaining the same temperature and oxygen flow rate. The mixture was then filtered while hot after the reaction was complete, and the filtrate was quantitatively analyzed by gas chromatography (internal standard method). The conversion rate of o-chlorotoluene was 97.6%, and the yield of o-chlorobenzoic acid was 95.3%.

[0046] Example 4: Catalytic oxidation of o-chlorotoluene to prepare o-chlorobenzoic acid 500 g of o-chlorotoluene was added to a 1000 ml glass reaction flask, along with 10.0 g of the catalyst obtained in Preparation Example 4 (2% of the mass of o-chlorotoluene). The mixture was heated to 130 °C, and oxygen was introduced at a rate of 250 ml / min (standard conditions). After reacting for 4 hours, the temperature was raised to 160 °C, and the reaction was continued for another 8 hours while maintaining the same temperature and oxygen introduction rate. The mixture was filtered while hot after the reaction was complete, and the filtrate was quantitatively analyzed by gas chromatography (internal standard method). The conversion rate of o-chlorotoluene was 87.5%, and the yield of o-chlorobenzoic acid was 80.9%.

[0047] Example 5: Catalytic oxidation of o-chlorotoluene to prepare o-chlorobenzoic acid 500 g of o-chlorotoluene was added to a 1000 ml glass reaction flask, along with 10.0 g of the catalyst obtained in Preparation Example 5 (2% of the mass of o-chlorotoluene). The mixture was heated to 130 °C, and oxygen was introduced at a rate of 250 ml / min (standard conditions). After reacting for 2 hours, the temperature was raised to 160 °C, and the reaction was continued for 6 hours while maintaining the same temperature and oxygen introduction rate. The mixture was filtered while hot after the reaction was complete, and the filtrate was quantitatively analyzed by gas chromatography (internal standard method). The conversion rate of o-chlorotoluene was 99.3%, and the yield of o-chlorobenzoic acid was 98.2%.

[0048] Example 6: Catalytic oxidation of o-chlorotoluene to prepare o-chlorobenzoic acid 500 g of o-chlorotoluene was added to a 1000 ml glass reaction flask, along with 10.0 g of the catalyst obtained in Preparation Example 6 (2% of the mass of o-chlorotoluene). The mixture was heated to 130 °C, and oxygen was introduced at a rate of 250 ml / min (standard conditions). After reacting for 2 hours, the temperature was raised to 160 °C, and the reaction was continued for another 7 hours while maintaining the same temperature and oxygen introduction rate. The mixture was then filtered while hot after the reaction was complete, and the filtrate was quantitatively analyzed by gas chromatography (internal standard method). The conversion rate of o-chlorotoluene was 96.4%, and the yield of o-chlorobenzoic acid was 92.5%.

[0049] Example 7: Catalytic oxidation of o-chlorotoluene to prepare o-chlorobenzoic acid 500 g of o-chlorotoluene was added to a 1000 ml glass reaction flask, along with 10.0 g of the catalyst obtained in Preparation Example 7 (2% of the mass of o-chlorotoluene). The mixture was heated to 130 °C, and oxygen was introduced at a rate of 250 ml / min (standard conditions). After reacting for 3 hours, the temperature was raised to 160 °C, and the reaction was continued for another 8 hours while maintaining the same temperature and oxygen introduction rate. The mixture was then filtered while hot after the reaction was complete, and the filtrate was quantitatively analyzed by gas chromatography (internal standard method). The conversion rate of o-chlorotoluene was 94.1%, and the yield of o-chlorobenzoic acid was 89.3%.

[0050] Example 8: Catalytic oxidation of o-chlorotoluene to prepare o-chlorobenzoic acid 500 g of o-chlorotoluene was added to a 1000 ml glass reaction flask, along with 10.0 g of the catalyst obtained in Preparation Example 8 (2% of the mass of o-chlorotoluene). The mixture was heated to 130 °C, and oxygen was introduced at a rate of 250 ml / min (standard conditions). After reacting for 4 hours, the temperature was raised to 160 °C, and the reaction was continued for another 8 hours while maintaining the same temperature and oxygen introduction rate. The mixture was filtered while hot after the reaction was complete, and the filtrate was quantitatively analyzed by gas chromatography (internal standard method). The conversion rate of o-chlorotoluene was 92.2%, and the yield of o-chlorobenzoic acid was 86.5%.

[0051] Example of effectiveness: Catalyst lifetime assessment 500 g of o-chlorotoluene was added to a 1000 ml glass reaction flask, along with 10.0 g of the catalyst obtained in Preparation Example 5 (2% of the mass of o-chlorotoluene). The mixture was heated to 130 °C, and oxygen was introduced at a rate of 250 ml / min (standard conditions). After reacting for 2 hours, the temperature was increased to 160 °C, and the reaction was continued for 6 hours while maintaining the reaction temperature and oxygen introduction rate. After the reaction was completed, the mixture was filtered while hot, and the filtrate was quantitatively analyzed by gas chromatography (internal standard method). The filter cake was used as catalyst and recycled under the experimental conditions described above. The experimental results are shown in Table 1. Table 1. Stability assessment of the catalyst 1 99.3 98.2 2 98.9 97.8 3 99.5 98.3 4 98.8 97.9 5 99.2 98.1 The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be included within the protection scope of the present invention.

Claims

1. A supported manganese-based catalyst, characterized in that, It includes: The active component and the support, wherein the support is SiO2 and the active component is a mixture of manganese oxide and cobalt oxide.

2. A method for preparing a supported manganese-based catalyst, characterized in that, The method includes: Step S1: Dissolve Na2SiO3·9H2O, sulfuric acid, manganese-cobalt mixture and Na2CO3 in water to obtain solution A, solution B, solution C and solution D respectively; Step S2: Under water bath conditions, solution A is introduced into the first microreactor as the dispersed phase by a metering pump, mixed with the continuous phase solution B, and then flows through the first residence tube. After mixing with solution C through a T-shaped tee, it is introduced into the second residence tube and then into the second microreactor. After mixing with the dispersed phase solution D, it is introduced into the polytetrafluoroethylene reaction tube. After the reaction, the precipitate is collected. Step S3: After centrifugation, washing, drying and calcination, the precipitate is obtained as the supported manganese-based catalyst.

3. The method for preparing a supported manganese-based catalyst according to claim 2, characterized in that, In step S1, the concentration of Na2SiO3·9H2O in solution A is 0.01-0.5 mol / L; the concentration of sulfuric acid in solution B is 0.05-0.5 mol / L; the manganese-cobalt mixture includes MnCl2·4H2O and Co(NO3)2·6H2O in a molar ratio of 1:0.05-1.0; the total concentration of metal salts in solution C is 0.1-0.5 mol / L; and the concentration of Na2CO3 in solution D is 0.1-1.0 mol / L.

4. The method for preparing a supported manganese-based catalyst according to claim 2, characterized in that, In step S2, the water bath temperature is 20-50℃; the flow rates of solution A and solution C are the same, at 3-7.5 mL / min; the flow rate of solution B is adjusted so that the pH value of the solution after mixing solution A and solution B is 8.3-8.

7.

5. The method for preparing a supported manganese-based catalyst according to claim 2, characterized in that, Both the first microreactor and the second microreactor are membrane dispersion microreactors.

6. The method for preparing a supported manganese-based catalyst according to claim 2, characterized in that, In step S2, both the first and second residence tubes are polytetrafluoroethylene tubes with an inner diameter of 3 mm; the residence time in the first residence tube is 5-20 min, and the residence time in the second residence tube is 3-10 min. The polytetrafluoroethylene reaction tube has a volume of 50 mL and an inner diameter of 3 mm.

7. The method for preparing a supported manganese-based catalyst according to claim 2, characterized in that, In step S3, the drying temperature is 90-110℃; the calcination temperature is 450-800℃; the calcination time is 3.5-4.5h; and the heating rate is 3-7℃ / min.

8. A method for preparing o-chlorobenzoic acid, characterized in that, It uses the supported manganese-based catalyst as described in claim 1 or the supported manganese-based catalyst prepared by any one of the methods described in 2-7 as a catalyst to catalyze the preparation of o-chlorobenzoic acid from o-chlorotoluene under oxygen-introduced conditions.

9. The method for preparing o-chlorobenzoic acid according to claim 8, characterized in that, The weight ratio of o-chlorotoluene to catalyst is 1:0.18~0.22; under standard conditions, the oxygen introduction rate is 240-260 mL / min.

10. The method for preparing o-chlorobenzoic acid according to claim 8, characterized in that, The reaction temperature is 130-160℃, and the reaction time is 8-14h.